The present invention relates to a cosmetic composition containing a cationic thickener, and more particularly to a cosmetic composition which can be suitably used as, for instance, hair-conditioner, hair-setting cosmetics, hair dressing cosmetics, various cosmetic cream and the like.
As a thickener for a cosmetic composition, extracts of natural products such as quince seed gum have been conventionally used, but there is a possibility that these extracts are deteriorated by a hungas, a bacterium and the like. Therefore, a thickener made of a synthetic resin has been used in recent years.
As the typical thickener of the synthetic resin, there have been known a thickener made of a crosslinked polyacrylic acid prepared by crosslinking a polyacrylic acid with allyl saccharose and then adjusting its pH (Japanese Examined Patent Publication No. 4141/1957) and a thickener prepared by crosslinking a polyacrylic acid with an alkenyl ether and then adjusting its pH (Japanese Unexamined Patent Publication No. 46586/1976) have been known.
When these thickeners are used in cosmetics for hair, scalp and skin, a hard film is formed after drying, therefore excellent setting property is imparted to hair. However, there occurs some problems that hair cannot be easily combed and that a phenomenon that a film which is formed on hair is peeled off, that is, flaking is easily generated.
Also, when an anionic base gel made of the crosslinked polyacrylic acid is used, since this anionic base gel has --COOH groups in its molecule, and its main structure is an anionic polymer prepared by neutralizing all or a part of the --COOH groups with NaOH, KOH, an amine or the like, when raw materials for cosmetics for hair and scalp such as a cationic polymer for setting containing a quarternary amine are added thereto, neutralization of electric charge occurs between the anionic base gel and the raw materials and thereby coagulation, cloudiness, turbidity and the like are sometimes caused.
Accordingly, polymers for setting which can be added to the anionic base gel are only nonionic polymers such as polyvinylpyrrolidone and vinylpyrrolidone-vinyl acetate copolymer, and anionic polymers represented by an alkanolamine solution of an acrylic resin.
Also, it is not desirable that an acidic material such as lactic acid or succinic acid, which is admitted as an excellent pH adjusting agent for skin, is added as a raw material for cosmetics to an aqueous cosmetic composition containing the anionic base gel since lowering of viscosity or transparency of the cosmetic composition occurs. Therefore, the use of the aqueous cosmetic composition has been limited.
On the other hand, as a base gel which forms a soft and flexible film after drying, there is known a base gel which is prepared by carrying out an aqueous emulsion polymerization of a crosslinkable monomer and a monomer having an amino group and then adjusting a pH value to increase its viscosity (Japanese Unexamined Patent Publication No. 133145/1982). However, since the monomer is easily hydrolyzed, when the crosslinkable monomer is hydrolyzed and then neutralized by an acid treatment, a cationic group is introduced into the crosslinkable monomer. As a result, since an anionic group and a cationic group coexist in the same molecular chain of an obtained polymer, the polymer sometimes does not become uniform.
Also, when N,N-dimethylaminoethyl methacrylate is used as a raw material of the gel, a desirable polymer cannot be obtained since hydrolysis is caused with violence during the polymerization reaction in water. In other words, this fact means that there cannot be used N,N-dimethyl-aminoethyl methacrylate which is widely and industrially used and known as a raw material for cosmetics having excellent properties, and that there is inconvenience in the selection of the starting monomer for the cationic base gel. Also, there is a defect that the contamination with an impurity such as a surface active agent cannot be avoided.
Also, U.S. Pat. No. 4,542,175 discloses a method of thickening an aqueous system containing an aqueous dispersion of a polymer comprising (A) 20 to 100% by weight of a basic unsaturated free radically polymerizable monomer having at least one basic nitrogen atom, (B) 0 to 95% by weight of a neutral unsaturated free radically polymerizable comonomer and 0 to 30% by weight of a neutral unsaturated free radically polymerizable comonomer, which is prepared by aqueous emulsion polymerization. However, a dialkylaminoalkyl (meth)acrylate having a short alkyl group like a N,N-dimethylaminoethyl methacrylate cannot be used as one of the components for the polymer since the dialkylaminoalkyl (meth)acrylate is easily hydrolyzed during its polymerization reaction in water. Moreover, there are some defects such that impurities such as a surface active agent are contained in the resulting aqueous dispersion of the polymer, and that the polymer does not become uniform.
In order to solve the above problems, there is proposed a gel made of a copolymer prepared by copolymerizing a (meth)acrylic acid ester such as N,N-dimethylaminoethyl acrylate as disclosed in Japanese Unexamined Patent Publication No. 106114/1992, an oxyalkylene di(meth)acrylate and a vinyl monomer such as N-vinylpyrrolidone as disclosed in Japanese Unexamined Patent Publication No. 106114/1992. However, the gel is not good in flexibility and gloss of its formed film.
An object of the present invention is to provide a cosmetic composition comprising a cationic thickener, which can be preferably blended with not only a cationic polymer for setting but also the other polymer for setting which cannot be mixed with an anionic thickener.
Another object of the present invention is to provide a cosmetic composition comprising a cationic thickener which forms a flexible film after drying and contains little impurities.
A further object of the present invention is to provide a cosmetic composition which can be suitably used as hand cream, hair cream and the like.
A still further object of the present invention is to provide a cosmetic composition comprising a cationic thickener which is excellent in moisture resistance when the cosmetic composition is used together with a polymer for setting.
A still further object of the present invention is to provide a cosmetic composition which can be suitably used as a hair grooming preparation which shows excellent adhesive property to hair based upon the cationic polymer for setting.
These and other objects of the present invention will become apparent from the description hereinafter.